<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let chior=[];//合唱团
let duck={
    duckSinging:function(){
console.log('嘎嘎嘎');
    }
}
//999
for(let i=0;i<999;i++){
    if(checkIsDuck(duck)){
    chior.push(duck)
}
}
//只要有两条腿，并且嘎嘎嘎叫就是鸭子
let chick={
     duckSinging:function(){
      console.log('嘎嘎嘎');
     }
}
if(checkIsDuck(chick)){
chior.push(chick);}
/*
* @func 检验是否是鸭子
* @params obj ()
 @return boolean 
*
*/
function checkIsDuck(chick){
    if(chick.hasOwnProperty('duckSinging')
    &&
    typeof chick.duckSinging=='function' ) {
return true;
    }
return false;
}

if(chior.length>=1000){
    console.log('招募工作已完成')
}
else{
    console.log('招募工作还未完成')
}
    </script>
</body>
</html>